The G2x does use the same WM8994; the software is different from Samsung phones and doesn't have compatibility with all of the same EQ features in Voodoo, but I have DSP manager for that
They sound great, in my opinion. They fall somewhere between my old CX400-II and Shure SE215 in terms of all-around sound quality. I prefer them to the CX, they don't have as much midbass hump, the treble is more natural (CX are slightly v-shaped) and the mids are more liquid, less grainy. Vocals have a little less air than the CX but have better timbre and sound noticeably more natural.
The bass is nicely extended, dynamics are good, overall a balanced sound with a slight lift in the bass. Actually they are similar to the SE215 in terms of presentation; dynamics aren't as good but the treble is more extended and soundstage has similar width; the SE215 is deeper, though. The whole sound is a touch granier than SE215 and it's not as detailed, especially in the mids, but overall I think it's a favorable comparison for the 8320, considering the cost of the SE215. My CX were about $75 on Amazon when I bought them; I realize now what a ridiculous ripoff that was. They are better sounding than apple buds or the crappy $50 noise cancelling Sonys that I see everyone wearing on the train, but compared to what's out there, I'd pay maybe $30-$40 for them.
That said, I really wish the 8320s had a more usable form factor...I commute via train and the isolation is crap...if they had the form factor of the CX or SE215, they would probably be my only IEM.